Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

204
FXUS63 KLOT 071513
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
913 AM CST Wed Jan 7 2026

.KEY MESSAGES...

- Areas of dense fog this morning, particularly across interior
  sections of northern IL. Improvement expected toward midday.

- Periods of rain are expected on Thursday. Southwest winds may
  become gusty Thursday night

- A storm system may bring a mix of rain and snow this weekend.

&&

.UPDATE...
Issued at 858 AM CST Wed Jan 7 2026

Quite a foggy day this morning. As visibilities dropped, a
dense fog advisory was issued for areas near and north of I-88
through 10 AM. Winds are starting to pick up to 5 to 10 mph,
which should help improve conditions. There is a non-zero chance
that the advisory may need to be extended an hour to 11 AM.
While there is lower confidence on the exact timing of
improvement, the winds increasing at least give confidence that
we should return to clearer visibilities by midday.

While it will be nice for the fog to eventually lift, cloud
cover will linger through the late morning and into the early
afternoon. HREF is suggesting clouds breaking up from south to
north this afternoon, but there is some skepticism in how
quickly sky cover improvement will occur. The main impact of
this is to today`s temperature forecast. A fairly stout
gradient is expected across I-80 with low 40s to the north
(upper 40s, maybe low 50s to the south). However, if clouds
were to clear out quicker (best chance of this south of I-80),
temperatures could verify higher than forecasted.

DK

&&

.DISCUSSION...
Issued at 334 AM CST Wed Jan 7 2026

Through Tonight:

Low stratus and mist (VSBYs 3-5 miles) remain persistent across
the entire area this morning. The main concern over the next
few hours that we will continue to monitor closely is whether or
not this deck of stratus will act to build down to the surface
as dense fog. There are signs that this may already be in the
process of occurring across parts of northwestern IL as slight
colder temperatures (upper 20s to low 30s) across eastern IA are
beginning to slowly ooze eastward across the Mississippi on
light westerly winds. We suspect as this continues to interact
with the very moist low-level airmass across northwestern IL
that VSBYs will be on a downward trend the remainder of the
overnight period, thus increasing the threat for a period of
dense fog for at least portions of the LOT CWA this morning. We
certainly could see the need to hoist a dense fog advisory
within the next few hours to cover through the mid to late
morning period for a good chunk of my interior northern IL
counties (especially west of Chicago). However, before locking
into an advisory, we plan to continue monitoring trends over the
next couple of hours.

The low clouds and fog are likely to be slow to improve later
this morning. In fact, most of this cloud cover will likely not
erode until sometime this afternoon as the lower-level begins to
shift southerly. Northeastern IL is expected to be the slowest
to improve this afternoon. As a result, temperatures in this
area may struggle to warm much above the lower 40s, particularly
near the WI state line. However, farther south, scattering
afternoon cloud cover should help conditions warm into the mid
40s in and around the I-80 corridor. Some areas well south of
I-80 could even end up around 50 this afternoon.

Southerly winds and warm air advection will persist tonight in
advance of our next approaching weather system taking shape
across the Plains. This is expected to result in another mild
night, with overnight low temperatures expected to remain in the
mid and upper 30s. Higher level cloud cover will also be on a
quick increase overnight in advance of the Plains weather
system.

KJB


Thursday through Tuesday:

At the start of Thursday, we should find a warm front quickly
lifting north across the lower Midwest in advance of an
impending surface low. This storm will strengthen sharply over
the south- central Plains during the earlier part of Thursday
before jetting northeast into the region. Widespread rain should
overspread the CWA during the afternoon and remain through the
day. There`s now solid model agreement that the low center will
pass through north central or northwestern IL which would favor
the axis of steadiest rain and highest QPF staying just out of
reach to our northwest. Highest exceedance probs from the global
ensembles run along eastern IA, far northwestern IL, and into
southern WI. A pretty good consensus among models for around our
CWA is a few to several tenths of an inch through the night. A
newer signal though, especially among some of the higher res
camps coming into play, is for localized swaths of higher QPF
across the CWA beneath the storm`s low level conveyor and
along/ahead of the cold front. We`ll also have to keep any eye
on the potential for low-topped convection during the evening
and night. After the warm front lifts into the area, models have
upwards of a couple of hundred Joules of instability working
into mainly the southern half or so of the CWA. This environment
does not look supportive of anything more than an isolated
strike or two at this point, but with 50 to 60 kt of 925mb flow
ahead of the front, any convectively-driven showers may be able
to transport strong to even damaging wind gusts to the surface.
The potential for convection is greater with southern extent and
best convective chances exist across central and southern IL
where dewpoints are favored near and just above 60F. An SPC Day
2 marginal risk for severe wind currently extends as far north
as about Lincoln, IL. The widespread soaking rain should lift to
the north of the area earlier in the evening while the
convective potential will last into the overnight.

Efficient warm advection ahead of this storm will pull Thursday
afternoon temperatures into the lower 50s for many around the
area. However, it looks as though daily highs on Thursday may
occur late in the evening as the warm front surges across the
CWA. Temperatures at the start of Friday are forecast in the 40s
to near 50, and probably won`t move much during the day as cold
advection may offset diurnal heating. Friday looks rather gray
stuck beneath low hanging stratus and perhaps period of drizzle.

Another very dynamic system is slated to move across the region
on Saturday. There`s still quite the spread in possible
outcomes, so won`t get into too many details at this point. But
guidance has been favoring a push of rain or a wintry mix early
Saturday before transitioning to a potential for periods of snow
showers during the afternoon and evening. The passing surface
low will move well ahead of the sprawling upper vort max which
will promote additional snow showers through the night and into
Sunday. There isn`t really any support for anything more than a
couple of inches of accumulation, but uncertainty is very high
at the moment and would not put any stock into snow totals right
now. But late Saturday and Sunday are also shaping up to be
rather windy, which does add some blowing/drifting snow concerns
depending on the nature of the snow showers. Stay tuned while
more is ironed out with this system over the coming days.

Doom

&&

.AVIATION /12Z TAFS THROUGH 18Z THURSDAY/...
Issued at 536 AM CST Wed Jan 7 2026

Key messages for the 12Z TAF period:

*IFR to LIFR into this afternoon

The area is socked beneath IFR and LIFR cigs early this
morning. MVFR vsbys are also found across a number of sites with
some IFR west of Chicago. Conditions are not expected to change
all that much through mid to late morning. Periods of VLIFR
will be possible, primarily at DPA and RFD where intermittent
200 ft cigs have been noted. It`s also possible that
visibilities come down some closer to dawn, but confidence in
this occurring is low. IFR coverage should gradually start to
break up toward late morning and a return to VFR is anticipated
by early to mid afternoon. From there, VFR is expected for the
remainder of the period.

Meanwhile, west winds below 10 kt this morning will back to
southerly this afternoon. Direction should largely favor SSW
through the night, except for the early to mid evening period
when direction could push east of south (170-160). Magnitude
should mostly remain below 10 kt but can`t rule out some gusts
into the teens kts before winds increase after sunrise Thursday.

Doom

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Dense Fog Advisory until 10 AM CST this morning for ILZ003-
     ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011-ILZ012-ILZ013-
     ILZ020-ILZ103-ILZ106.

IN...None.
LM...None.

&&

$$

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